Variations of mitotic activity in the adenohypophysis of male Rats during a 24-Hour cycle

Jc, Nouët; Kujas, M

doi:10.1007/bf00218973

Cited by 29 publications

(18 citation statements)

References 9 publications

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“…This conflicting result may be due to the fact that there is a diurnal cycle of mitosis in pituitary cells (Nouet and Kujas, 1975) and that the interval of the metaphase is too short to encounter mitotic division.…”

Section: Discussionmentioning

confidence: 99%

Compensatory development of immature LH cells after long-term gonadectomy: An immunocytochemical, electron microscopic and cell count study.

Kihara

1984

Endocrinol Japon

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Section: Discussionmentioning

confidence: 99%

Compensatory development of immature LH cells after long-term gonadectomy: An immunocytochemical, electron microscopic and cell count study.

Kihara

1984

Endocrinol Japon

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“…Whether peak activity occurs during the night (Carbajo-Perez et al 1991, Oishi et al 1993 or during the day, or as one peak of mitotic activity (McNicol & Carbajo-Perez 1999) or two (Nouet & Kujas 1975) is unclear. Differences in age, sex and breed of rats aside, the very low prevalence of mitotic figures and the unpredictable effects of stress in different holding facilities is likely to make this issue hard to resolve.…”

Section: Circadian Rhythmicity Of Trophic Activitymentioning

confidence: 99%

Physiological implications of pituitary trophic activity

Levy

2002

Journal of Endocrinology

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A complete inventory of pituitary trophic responses depends on precise estimates of mitotic activity and apoptotic events, and accurate characterization and quantification of pituitary cell subtypes irrespective of previous and current physiological demand. For a discrete structure that has been so extensively studied, it is disappointing but perhaps not surprising that none of these measures is available and therefore that the relative contributions to changes in the proportions of pituitary cellular subpopulations of trophic activity, differentiation of pluripotent cells and variations in the secretory profiles of apparently committed cells remain almost impossible to determine. To fully appreciate the extent of this dilemma, it should be remembered that conservative estimates of the proportion of corticotrophs in the rat anterior pituitary under basal conditions vary over twofold and that it is still not clear whether the apparent threefold increase in mammotrophs during pregnancy is the result of maturation of uncommitted cells, transdifferentiation of other cells such as somatotrophs, cell division, or a mixture of all three. Equally, while it has been known for some time that adrenalectomy results in a transient increase in anterior pituitary mitotic activity and appropriately timed supraphysiological glucocorticoid replacement with a wave of apoptosis, the precise identity of the cells involved in both of these responses is open to question. Thus, although many of the physiological stimuli associated with apparent changes in the proportions of pituitary cellular subpopulations are known, the precise mechanism of the changes and the consequences of the same remain obscure. This review summarizes the limited literature on pituitary trophic activity and asks what, if anything, analysis of pituitary trophic activity using current technology can tell us.

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“…Hunt and Hunt (1966) found drastic changes in mitotic rates during different phases of the estrous cycle in female rats, and the number in mitotic cells in male rats has been observed to increase and decrease over the course of 24 hours (Nouet and Kujas, 1975). More recently, immunohistochemical staining of 36-kd proliferating cell nuclear antigen (PCNA) (Miyachi et al, 1978;Bravo and Celis, 1980), identified as an auxiliary protein of DNA poly-merase-6 (Bravo et al, 1987;Prelich et al, 1987), has been used for studying cell kinetics.…”

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confidence: 95%

Cellular proliferation in the anterior pituitary gland of normal adult rats: Influences of sex, estrous cycle, and circadian change

Oishi¹,

et al. 1993

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Proliferative activity of the anterior pituitary gland in 10 week-old male and female rats under normal conditions was investigated by counting mitotic figures and using single and double immunostaining of 5-bromo-2'-deoxyuridine (BrdU), proliferating cell nuclear antigen (PCNA), and six pituitary hormones. To determine which proliferative changes depend on the estrous cycle and circadian changes, respectively, six groups of female and two groups of male rats were studied at various times of day. Additionally, BrdU-incorporated cells were further classified by the six types of hormones they contained, or as immunonegative cells. Cell proliferative activity in the females fluctuated drastically with the highest activity in estrus and the lowest in diestrus. In the males, proliferative activity was at a relatively low level, and was similar to that in females in proestrus or early estrus, with the greater activity at night. Identified by their pituitary hormones, the distribution of the proliferating cells was almost the same in each sex, with prolactin (PRL) cells accounting for the highest proportion, followed by growth hormone (GH) cells, and adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) cells. These percentages agreed well with previously reported levels of cell types among all pituitary cells of the rat. It is therefore suggested that the life span and cycle of rat pituitary cells does not differ among cell types. In another test, male and female rats were given BrdU continuously via an osmotic pump for 8 days to compare cell proliferative activity between sexes, exclusive of the influence of estrous cycle and circadian changes. In this way, we were able to demonstrate that the cumulative incorporation of BrdU in females was consistently twice as high as in males over a constant period of time, and to conclude that cell renewal occurs at a doubled rate in the pituitary of female rat.

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Variations of mitotic activity in the adenohypophysis of male Rats during a 24-Hour cycle

Cited by 29 publications

References 9 publications

Compensatory development of immature LH cells after long-term gonadectomy: An immunocytochemical, electron microscopic and cell count study.

Compensatory development of immature LH cells after long-term gonadectomy: An immunocytochemical, electron microscopic and cell count study.

Physiological implications of pituitary trophic activity

Cellular proliferation in the anterior pituitary gland of normal adult rats: Influences of sex, estrous cycle, and circadian change

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